A number added to the difference between triple the number and thirteen

4x-13

Step-by-step explanation:

Let the number is x.

We know that triple of a number is 3 times that number i.e. 3x

The difference between triple the number and thirteen 3x-13

Now, we need to add a number to the difference between triple the number and thirteen. So, the expression can be written as :

x+3x-13 = 4x-13

Hence, the expression is  (4x-13).

(sin 42)/31. = sinx)/37

sinx = 37 (sin42)/31

= 37× 0.66/31 = 0.787

x= 51.9

other angle opposite to y = 180-51.9-42

= 180- 93.9 =86.1

so

sin42)/31 = sin 86.1)/y

0.021 = 0.997 /y

y= 0.997/0.021 =47.47

practice. practice. practice.